Holographic display system with conjugate image removal for a motor vehicle

Abstract

A holographic display system for a motor vehicle includes a coherent light source for generating a beam of coherent light and a spatial light modulator (SLM) having a two-dimensional pixel array, which is encoded with a hologram for modulating a phase of the coherent light. The SLM generates a first diffracted beam associated with a main image and a second diffracted beam associated with a conjugate image, where the first and second diffracted beams are angularly spaced from one another by a first angle. The system further includes an optical component for angularly spacing the first and second diffracted beams from one another by a second angle that is larger than the first angle. The system further includes a display surface receiving the first diffracted beam from the optical component to display the main image, with the display surface being free of the second diffracted beam.

What is claimed is: 
     
       1. A holographic display system for a motor vehicle, the holographic display system comprising:
 a coherent light source for generating a beam of coherent light; 
 a spatial light modulator (SLM) comprising a two-dimensional pixel array for modulating a phase of the coherent light and generating a first diffracted beam associated with a main image and a second diffracted beam associated with a conjugate image, where the first and second diffracted beams are angularly spaced from one another by a first angle, wherein the SLM comprises a liquid crystal on silicon (LCoS) SLM and the SLM is capable of producing a phase shift within a range between 0 and 2π, where an actual range of the phase shift is not equal to 2π; 
 an optical component for transmitting at least one of the first and second diffracted beams and angularly spacing the first and second diffracted beams from one another by a second angle that is larger than the first angle, and the optical component comprises a diffractive grating for diffracting at least one of the first and second diffracted beams; 
 a display surface disposed relative to the optical component to receive the first diffracted beam from the optical component and display the main image, with the display surface being free of the second diffracted beam; and 
 a computer comprising:
 a processor coupled to the coherent light source and the SLM; and 
 a memory including instructions such that the processor is programmed to control the two-dimensional pixel array of the SLM that generates the first and second diffracted beams. 
 
 
     
     
       2. The holographic display system of  claim 1  wherein the coherent light source is a LASER. 
     
     
       3. A motor vehicle comprising:
 a body defining a passenger cabin; 
 a plurality of reflective surfaces surrounding the passenger cabin, with the reflective surfaces including at least one of a mirror, a front windshield, a rear windshield, a sunroof, and a plurality of side windows surrounding the passenger cabin; and 
 a holographic display system coupled to the body and comprising:
 a coherent light source for generating a beam of coherent light; 
 a spatial light modulator (SLM) comprising a two-dimensional pixel array for modulating a phase of the coherent light and generating a first diffracted beam associated with a main image and a second diffracted beam associated with a conjugate image, where the first and second diffracted beams are angularly spaced from one another by a first angle, wherein the SLM comprises a liquid crystal on silicon (LCoS) SLM and the SLM is capable of producing a phase shift within a range between 0 and 2π, where an actual range of the phase shift is not equal to 2π; 
 an optical component for transmitting at least one of the first and second diffracted beams and angularly spacing the first and second diffracted beams from one another by a second angle that is larger than the first angle, wherein the optical component comprises a refractive prism; 
 a display surface disposed relative to the optical component to receive the first diffracted beam from the optical component and display the main image, with the display surface being free of the second diffracted beam, wherein the display surface comprises a portion of a combiner glass on at least one of the front windshield, the rear windshield, the sunroof, and the side windows; and 
 a computer comprising:
 a processor coupled to the coherent light source and the SLM; and 
 a memory including instructions such that the processor is programmed to control the two-dimensional pixel array of the SLM that generates the first and second diffracted beams. 
 
 
 
     
     
       4. The motor vehicle of  claim 3  wherein the coherent light source is a LASER. 
     
     
       5. A method of operating a holographic display system for a motor vehicle, the holographic display system including a coherent light source, a spatial light modulator (SLM) comprising a two-dimensional pixel array, an optical component, a display surface, and a computer having a processor and a memory, the method comprising:
 generating, using the coherent light source that is a LASER, a beam of coherent light; 
 modulating, using the SLM, a phase of the coherent light, where an actual range of the phase shift is not equal to 2π, that generates a first diffracted beam associated with a main image and a second diffracted beam associated with a conjugate image, where the first and second diffracted beams are angularly spaced from one another by a first angle, wherein the SLM is a liquid crystal on silicon (LCoS) SLM, and wherein one of the first and second diffracted beams are diffracted using a diffractive grating; 
 angularly spacing, using the optical component, the first and second diffracted beams from one another by a second angle that is larger than the first angle; and 
 controlling, using the processor, the two-dimensional pixel array of the SLM that generates the first and second diffracted beams.